Microplastic pollution in the Ganga River: A state-of-the-art review of pathways, mechanisms, and mitigation Open Access

The Ganga River, a lifeline for millions and a symbol of cultural and spiritual reverence, is grappling with a severe environmental challenge, i.e., MP (MP) pollution. A 2,500-km stretch of the Ganga River shows diverse ecosystems and numerous communities along its banks (Simon & Joshi 2022).

However, the influx of MPs (tiny plastic particles smaller than 5 mm) into Ganga water has raised significant ecological and health concerns (Gupta et al. 2024a). These contaminants originate from various sources, including urban runoff, industrial discharges, agricultural land, and human activities (Haque 2022; Talukdar et al. 2023).

A global issue of MP pollution with localized impacts is profoundly found in the region of the Ganga River basin (Drew 2011). The nature of MP shows resistance to natural degradation and the result of this accumulates in aquatic ecosystems continuously (Pandey et al. 2021). Bioaccumulation of MPs has a diverse and deadly impact on the health of organisms. Aquatic organisms, including fish and invertebrates, often ingest MPs, mistaking them for food (Sau et al. 2023). This ingestion results in physical harm and chemical exposure, with the potential for toxins to bioaccumulate, thereby disrupting food webs and biodiversity (Bellasi et al. 2020; Farooq et al. 2023). Studies have documented MP presence in various species within the Ganga, highlighting risks for both wildlife and human health (Shaikh & Shaikh 2021; Mishra et al. 2023). These particles also adsorb harmful pollutants, such as heavy metals and persistent organic chemicals, which intensifies their toxicological effects (Veerasingam et al. 2020).

The Ganga River, which flows through heavily populated and industrialized areas, becomes a repository for these pollutants and hurts both water quality and ecological system (Chinglenthoiba et al. 2023). Millions of people rely on the river for drinking water, fishing, and agriculture. The contamination of these water resources threatens public health and compromises the safety of aquatic food products (Farooq et al. 2023). This is particularly concerning in communities that depend on the river for their livelihoods, where MP contamination can lead to economic losses in fishing and tourism industries (Mahmud et al. 2022).

Financially poor cities often lack adequate waste management and treatment facilities as a result of this addition of MPs into the river system, knowingly or unknowingly (Vanapalli et al. 2021). Urban areas along the river, such as Varanasi and Kolkata, contribute significantly to this pollution via direct inputs like stormwater runoff, wastewater discharges, and littering (Vaid et al. 2021). Wastewater treatment plants (WWTPs) situated at the bank of river or near to river Ganga are either partially functional or not working for the effective removal of MPs and pollutants (Chaudhary & Suthar 2023). Beyond environmental health consequences, MP pollution in the Ganga has significant socio-economic and cultural ramifications (Sivadas et al. 2022).

Culturally, the Ganga holds immense significance in Hinduism, and its pollution represents not only an environmental issue but also a profound spiritual and ethical crisis. Efforts to clean the river are therefore intertwined with cultural preservation, underscoring an urgent need for effective interventions to restore the river's health (Rajan et al. 2023; Rose et al. 2023).

Current research on MPs in the Ganga River basin addresses important aspects of their distribution, characterization, and potential health impacts. However, gaps remain that limit our understanding of MP pollution in this critical waterway. One key gap is the limited research on the seasonal and temporal dynamics of MP distribution across different river segments. While studies such as Singh et al. (2024a) and Chaudhary & Suthar (2023) have explored these variations to some extent, comprehensive seasonal data is necessary to understand the full impact of monsoon-related changes in MP dispersion and concentration (Sarkar et al. 2019; Napper et al. 2021). Additionally, while urbanization and industrial activities are acknowledged as significant contributors, more studies are required to elucidate the roles of various point and non-point pollution sources, especially in heavily urbanized areas like the Ganga-Brahmaputra delta (Neelavannan et al. 2023; Rajan et al. 2023). Another overlooked area is the interaction between MPs and co-pollutants such as heavy metals, which could lead to compounded ecological risks. Vaid et al. (2022) discuss co-contamination, but this complex interaction warrants further investigation across the basin. Lastly, studies are also needed to address the bioaccumulation pathways and the potential for trophic transfer of MPs within aquatic food webs, especially given local dietary practices involving riverine fish (Badola et al. 2023). Bridging these gaps will enable more effective policy interventions and a holistic understanding of MP pollution in the Ganga ecosystem.

This comprehensive review aims to elucidate the various pathways of MP contamination in the Ganga River, highlighting the sources, mechanisms, and implications of this pervasive pollutant. By synthesizing current knowledge and identifying gaps, this review seeks to inform stakeholders and guide future research and policy efforts to mitigate the impact of MPs on one of the world's most important rivers.

To develop a comprehensive review of MP pollution in the Ganga River, a structured and systematic search was conducted across multiple databases, including Scopus, PubMed, SpringerLink, ScienceDirect, Wiley Online Library, and Web of Science. The search covered literature published between 2009 and 2024, aiming to ensure the inclusion of recent studies on MP pollution pathways, sources, mechanisms, and mitigation strategies specific to the Ganga River. The search employed combinations of keywords such as:

• ‘MP Pollution’ along with ‘Ganga River’, ‘Ganges River’, ‘India’, ‘Plastic Pathways’, ‘Plastic Sources’, ‘Wastewater Discharge’, ‘Solid Waste’, ‘Atmospheric Deposition’, ‘Riverine Transport’, ‘Religious and Cultural Activities’, ‘Polyethylene’, ‘Polypropylene’, ‘Polystyrene’, ‘Pollution Mitigation’, and ‘Environmental Impact’.

• Additional combinations included terms related to specific types of MP pollution, such as ‘Synthetic Fibers’, ‘Plastic Fragments’, ‘Agricultural Runoff’, and ‘Domestic Wastewater’.

No language restrictions were applied. Each article's title and abstract were assessed for relevance according to inclusion and exclusion criteria, and the full text was reviewed if deemed relevant.

• (a) Studies focusing on MP pollution pathways, mechanisms, and sources specific to the Ganga River, including inputs from urban, industrial, agricultural, and religious sources.

• (b) Research detailing the composition, characteristics, and types of MPs found in the Ganga River, including studies on dominant polymer types (e.g., polyethylene, polypropylene) and shapes (e.g., fibers, fragments, films).

• (c) Investigations into the environmental impact of MP pollution on water, soil, and sediment within the Ganga River system.

• (d) Studies exploring mitigation strategies or frameworks aimed at reducing or preventing MP pollution in the Ganga River, such as waste management, policy interventions, and community-based initiatives.

• (e) Articles published in peer-reviewed journals or conference proceedings that provide empirical data or review analysis relevant to MP pollution in the Ganga River.

• (i) Studies focused on rivers outside India or unrelated water systems not directly comparable to the Ganga River in terms of environmental context.

• (ii) Research on MP pollution from sources not relevant to the Ganga River or its tributaries, such as marine or other non-fluvial environments.

• (iii) Articles without full text availability, and those published in languages other than English.

• (iv) Case studies, letters, editorials, and other non-primary research publications that do not contribute empirical data or comprehensive reviews.

• (v) Studies where data are limited to generic plastic pollution without specific insights into MPs.

Urban areas along the Ganga River generate substantial amounts of wastewater that often contain MPs. The Ganges River generates 315 tons of plastic waste daily, equivalent to 79 elephants (Shivhare & Sharma 2023). Many urban areas in the Ganges catchment reportedly produce large amounts of wastewater, most of which end up in the river through untreated or partially treated systems (Dutta et al. 2020). Laundry wastewater is a major source of synthetic microfibres in river systems (Vardar et al. 2021). Holy cities situated on the riverbank are also responsible for adding MP due to higher anthropogenic activities, lack of efficient sewage system, mass participation in holy bathing (Kumar et al. 2012), and leakage from WWTPs (Kay et al. 2018). The Ganges River system recorded a 41 m²day⁻¹ MP presence (Napper et al. 2023). Table 1 shows the pathways through which MPs enter the Ganga River, along with detailed characteristics.

MPs are found in household wastewater as pieces from degraded plastic goods, microbeads from personal care products (PCCPs) and fibers from synthetic textiles. Primary sources of MPs at domestic and industrial levels are related to cosmetics, PCCPs, industrial abrasives, powders for 3D printing, etc. PCCPs include washing products, skin exfoliators, and toothpaste (Islam 2019). They contain MPs or microbeads in the product for accelerating cleaning or coloring function (Napper & Thompson 2016). A secondary type of MP is generally generated from the breakdown of bigger plastic items such as fishing nets, bottles, and bags (Kozioł et al. 2022). Further physical, chemical, and biological processes and exposure to UV radiations turned them into MP.

With an estimated 1.5 Mt of MPs entering the ocean annually (Boucher & Friot 2017) and the majority being carried from the land surface (Siegfried et al. 2017), the marine environment is thought to be a primary sink for MPs. MPs are transported by rivers from terrestrial surfaces into marine ecosystems, and this process is crucial. The escalation of MP pollution in rivers and the ocean has consequently drawn significant attention from world scientists. According to recent studies, large concentrations of MPs have been found in river surface water (Li et al. 2023). Previous research by Napper et al. (2021) suggests that the Ganges river system may discharge as much as 1–3 billion (109) MPs into the Bay of Bengal, which is the northeastern region of the Indian Ocean, on a daily basis. In the surface water of a river that runs from the Indian region of Patna to Rishikesh, or MPs, have been discovered. The highest concentration of MPs was found in surface water samples from Kanpur city. The predominant MPs were filamentous ones, and the concentrations of white/transparent polymers were higher (Rajan et al. 2023).

Wastewater treatment plant (WWTP) discharge is a significant point source of MP pollution. Urban areas discharge untreated sewage into rivers due to clogged sewers and malfunctioning pumping stations (Tariq & Mushtaq 2023). Of the Ganga's pollution load, untreated discharges from industries and cities account for over 75% (Dwivedi et al. 2018). Most plastic litter enters the marine environment through rivers and comes from land-based sources and inland locations (urban runoffs) (Mihai et al. 2022). When garments are washed, synthetic fibers are released into sewage or urban runoff, which is then disposed of in urban watershed systems (Dris et al. 2016; Sarkar et al. 2019). Many researchers have reported on the contribution of sewage mixing and urban runoff to the loading of MPs in urban rivers (Ding et al. 2019; Laermanns et al. 2021; Singh et al. 2021). Nayal & Suthar (2022) have reported that a number of factors may contribute to the presence of MP in urban rivers, including human encroachment near river banks, illegal discharge of urban solid waste in river catchment areas, and the immediate disposal of sewage and industrial effluents. Similar results were found in a study by Napper et al. (2023) examining atmospheric deposition in urban and rural settings. They found that while the average deposition rate in urban environments was 123.2 ± 30.8 MP m⁻²day⁻¹, the average deposition rate in rural environments was only 33%, at 40.1 ± 10 MP m⁻² day⁻¹.

The primary cause of MP pollution in the Ganga River is littering and the illegal dumping of garbage into public places. Therefore, the environment is degraded. Littering is the careless disposal of small waste articles from their place of deposit (Lebreton & Andrady 2019). On the other hand, illegal dumping is the deliberate placing of more significant amounts of waste into sites that are not allowed. That is, these granules degrade into MPs through the environmental conditions of sunlight and the action of water into Ganga (Prapanchan et al. 2023). Then, these are swept into the Ganga through surface runoff, wind, and direct deposition into the river. Instead, it is a significant threat to aquatic life and human life because it may be in the food chain (Jambeck et al. 2015). Equally important are efforts through stiffer laws and regulations, raising public awareness, and efficient waste management infrastructure to minimize littering and illegal disposal that would pose the biggest threat to the river ecosystem.

Most importantly, the landfills are open and near the bank of the Ganga River, acting as a significant source of MPs, making it highly risky for river ecology (Arora et al. 2024). Landfills are not lined, so the MPs directly leach into the river when it rains considerably, and surface runoff increases (Cordova & Riani 2021). Many studies have consistently pointed this out. By examining the paper by Cordova & Riani (2021), one can conclude that the leachates of the landfills would carry high amounts of MP particles and boost the pollution level further, as they have been observed to have a good amount of MP particles within them. Equally, Vaid et al. (2021) found a significant positive relationship between landfill proximity to river banks and an increased concentration of MPs in tested water samples. Recent studies by Singh et al. (2021) further confirm that MPs from landfills reach Ganga sediments, thus portending ecologic risks in the long run. The paper justifies that in river settings, MPs can be persistent. Even monsoonal-induced variation and flushing do not lessen the number of MPs. However, Roy et al. (2023) reported that the bioaccumulation of MPs into aquatic organisms could cause a subtle increase up the food chain that can eventually turn into potential hazards for human health. The current findings underscore the pressing need for development and improved waste management practices, as well as containment thereof, to reduce the leaching of landfills in improving the Ganga River.

These tiny plastic particles, among other things, are suspended in air and would eventually settle on the water surface or be washed into the Ganga with rainfall. The suspended MPs may originate in urban and industrial activities and could attain a reasonable distance through atmospheric transport before finally getting deposited into aquatic environments. With recent research works pointing toward this new direction, the importance of airborne MPs has been emphasized. For instance, Allen et al. (2019) estimated MP transfer to occur over distances more than 95 km from its origin and with significant deposition occurring in remote mountain catchments. Similar studies were carried out by Zhang et al. (2017), who established that MPs exist in all the remote parts of the Tibetan Plateau, indicating that pollutants can be transferred over long distances. Further, Brahney et al. (2020) found that significant quantities resulted in high MP loads from atmospheric deposition even in protected and remote areas, which further emphasizes the widespread nature of this pollution pathway. These results do imply comprehensive efforts involving the management and mitigation of airborne MPs on the Ganga Riverfront.

Wind action is one of the chief transport processes by which MPs enter the Ganga. Wind can blow lightweight plastic debris from areas such as urban centers and agricultural fields into the river. Once in the river, these plastics break into MPs under environmental factors such as UV radiation and mechanical abrasion. Research has evidenced that the contribution of wind-induced plastic waste may be a significant proportion of the total MP load into riverine systems. For instance, it has been suggested that a substantial part of plastic waste found in rivers must be from land-based sources as influenced by the action of wind (Alimi et al. 2018). Further observations from the field studies establish that wind-blown plastics are often deposited along the river banks and within the water column, further leading to the degradation of these deposited plastics into MPs (Jambeck et al. 2015). This pathway further establishes the requirement for comprehensive waste management plans to assist in controlling plastic pollution through wind dynamics in rivers (Lebreton et al. 2017). Recent studies have added a further emphasis on the nature of wind affecting sediment and plastic distribution within waterways. For instance, a study conducted in 2023 indicated that the dispersion of MPs over riverside bars results from a combination of the water level and wind intensity (Garello et al. 2023). Another 2023 study explored the effects of wind-driven turbulence on sediment resuspension, highlighting that high-density submerged vegetation can reduce turbulence intensity and impede sediment resuspension in water bodies like Lake Taihu (Wang et al. 2023). Figure 2 depicts the primary mechanisms through which MPs enter the Ganga River.

MPs can travel over extensive distances along the Ganga River, in which they aggregate and disperse through various mechanisms. Such hydrodynamic forces as the flow and turbulence of rivers can effectively transport MPs downstream. MPs are transported from urban sources into far-off, remote areas through riverine transport and, therefore can affect such distant ecologies. In 2023, researchers observed that MPs are carried in the water column and finally accumulate in river sediments and riverbanks. Garello et al.'s (2023) recent findings report a dependency on seasonal variability, with monsoon rains enhancing the mobilization and redistribution of MPs in the river Ganga. Based on the latter, the present studies converge on a common conclusion: that MP transport has become a complex mechanism for which monitoring and mitigation strategies should be built on a holistic approach (Barman et al. 2023).

The periodic variation in the volume of water flowing downstream could move MPs from upstream to downstream by natural forces of the river. The perennial flow of the Ganga River significantly contributes to the downstream movement of MPs, driven by both natural currents and seasonal fluctuations (Jambeck et al. 2015). Seasonal variations, such as during the monsoon season, give rise to abnormally high increases in both water volume and flow velocity, further enhancing the transport capacity of the river for MPs. Such elevated flows during the monsoon may support the redistribution and spread of MPs imbibed in sediments and those suspended in the water column (Rajan et al. 2023). Monsoonal floods have been proven to be one of the events responsible for this activity in the recent past. Gupta et al. (2024b) observed that the post-monsoon period was characterized by high MP concentrations in the Ganga River, indicating significant seasonal flood events in the mobilization and transportation of MPs along the river course.

MPs settling within sediment may be resuspended into the water column during flood events because of increased flow velocity and turbulence (Helinski et al. 2021). Aside from flood events, this could also happen due to activities carried out by anthropogenic means, such as dredging. The resultant high-flow velocities and turbulence, in combination with more pronounced forces acting on bodies of water, tend to suspend MPs that have already been deposited within the water body to be transferred downstream (Helinski et al. 2021). Under increased water force during high-flow events, enhanced scouring takes place, lifting MPs from sediments and reintroducing them to the water column. This significantly contributes to the downstream transport and redistribution of MPs (Hurley et al. 2018). Resuspension of MPs is also closely linked to anthropogenic activities, such as dredging. Dredging disrupts the bottom sediment, with MPs being remobilized into the water column in some cases, possibly traveling great distances (Hao et al. 2020).

Besides, the Ganga River has enormous numbers of tributaries, which may bring their inflow of MPs from the catchment areas. A significant part of its MP load comes from these tributaries acting as conduits of MP transport from the smaller rivers and streams and adjoining regions into the main river. For example, recent studies have shown that the tributaries such as Yamuna, Gomti, and Ghaghara contribute substantially to the MPs in the Ganga (Nayal & Suthar 2022; Mishra et al. 2023). These MPs come from different sources, such as urban runoff, agricultural activities, and industrial discharges, in the catchment areas of its tributaries. Thus, the interlinked river system guarantees that MPs from the tributaries ultimately reach the Ganga, where they increase the level of contamination (Napper et al. 2021).

The Ganga River holds immense cultural and religious importance, with many activities that account for the presence of MPs in the river. There is a manifold increase in the level of pollution during religious festivals, such as Navratri and Ganesha Chaturthi. For instance, during Navratri, about a year's pollution load was seen coming from the religious offerings and materials disposed into water bodies while performing rituals in the Ganga River water (Singh 2011). Among the activities that deposit plastic in the Ganga River are the numerous cultural practices, such as performing last rites. These mostly use plastic-incorporated materials, which find their way into the river system (Singh et al. 2022). Additionally, this is one significant contributor to pollution during religious and cultural functions, particularly during the festival of Ganesha Chaturthi. With this, lots of idols made of non-degradable materials eventually sink into the river during this festival, contributing to the MP load into the river load (de Koning 2022). The cultural and religious reverence for the river, while profound, complicates mitigation efforts, as interventions often risk being perceived as intrusions into sacred practices. To navigate these complexities, culturally sensitive approaches that engage religious leaders and incorporate eco-friendly alternatives for ritual materials are essential. Efforts are on the way to strike a balance between religious freedom and respect for environmental conservation.

Religious offerings and ceremonial items made of plastic are normally thrown into the river. These actions greatly lead to the existence of MPs in the Ganga River. Recent research has pointed out the seriousness of MP pollution caused by religious rites, most non-biodegradable materials used in offerings enter the river during festivals (Rajan et al. 2023). Similarly, a study conducted by Choudhury et al. (2022) established that MP levels were much higher in areas around religious places thus highlighting their impact on the health of the stream (Choudhury et al. 2022). To address this issue without undermining religious traditions, environmentally friendly initiatives such as providing biodegradable offerings or designating special disposal areas near religious sites could be introduced. Working with local communities to promote these practices could help preserve both the cultural significance of the Ganga and its ecological integrity. From these findings, it is evident that there should be improved methods of managing garbage as well as more enlightenment among people so as to reduce negative impacts brought about by ritual donations on the ecosystem of River Ganges.

Mass gatherings, specifically those like festivals and pilgrimages, are the most responsible when it comes to the issue of plastic waste, to name one. According to the research, during the events, such as Kumbh Mela, which are attended by millions, it was observed that the amount of plastic debris increased, which was the reason for a spike in MP concentrations (Rajan et al. 2023). In their study of the Yamuna River, which is one of the Ganga's main tributaries, Gupta et al. (2024a) backed these claims, citing the substantial growth of plastic waste during the festive season of Yamuna Chhath Puja. Napper et al. (2021) discovered that the Magh Mela events were also prone to MP contamination through their reports thus emphasizing the necessity for sustainable waste management of the site. Given the spiritual significance of these gatherings, solutions should involve partnerships with religious leaders and local authorities to educate devotees about environmentally respectful practices. Temporary waste management systems could be established during festivals, alongside biodegradable materials and disposal facilities for attendees. Safeguarding the Ganga from MP sewage requires various methods. Implementation of the waste management policy through the period of large events is key. To control the flow of plastics, organizations need to set up more garbage sites and encourage the use of materials that rot away easily (Rajan et al. 2023). It is also important for them to tighten laws governing disposal both in industries as well as homes. If MPs get into the river system they could wreak havoc so factories must start using cleaner production methods and treat their wastewater properly (Gupta et al. 2024a). Public awareness and education campaigns can make a big difference in cutting down on the use of plastic and throwing it away. If people are encouraged to think of themselves as custodians of the environment, they will change the way they act and thus lower plastic waste (Napper et al. 2021). More so, we cannot do without frequent studies and supervision that will ensure we know everything concerning MP pollution dynamics well enough to come up with techniques aimed at reducing their effect. It is necessary that we create new methods that can be used to unearth as well as filter out these particles from our water sources (Rajan et al. 2023).

Investigations that have been done on Ganges River contamination with MPs indicate that there are distinct seasonal and spatial differences (Li et al. 2023). The amount of MPs was more during the rainy season with most of them ranging from 300 μm to 1 mm and being mainly blue and black fibers. Common polymers included polyacrylamide, polyamide, and polyvinyl chloride where several MPs were found to have hazard scores >1,000 which poses a health threat (Gupta et al. 2024a). The most frequent polymers found were identified as polyethylene (PE), polypropylene (PP), polystyrene (PS), polyethylene terephthalate (PET), polyacetylene (PA), and polyvinyl chloride (PVC). In surface waters of river Ganga, PP (36%) and PE (30%) dominated while PET (39%) was more common in sediment samples (Gupta et al. 2024a). Similarly, PE and PP were abundant in Brahmaputra and Indus rivers' sediments. The primary polymer at the international boundary crossing point for the River Ganga was rayon, whereas in the rivers of Prayagraj EVOH, PA, and PVC prevailed besides those found within the Ganga River system (Singh et al. 2024b).

In a different study, it was found that in most water sampling sites, white or colorless MPs were mostly found and film-shaped MPs were the most dominant in the water and sediment samples. Polyethylene was the most abundant polymer in all the samples collected (Singh et al. 2021). Likewise, Sarkar et al. (2019) found that PET (39%) and PE (30%) were the biggest plastic waste in Ganga River sediments followed by the distribution of meso and MPs which is different in the respective places. In the Ganges River, fibers (91%) and fragments (9%) were the dominant forms of MP particles. Higher concentrations of MPs were observed pre-monsoon compared to post-monsoon, with an estimated 1–3 billion MP pieces discharged into the Bay of Bengal daily (Napper et al. 2021). Moreover, PET plastic breakup was prevailing in Gangetic fishes (Badola et al. 2023). The research of Kukkola et al. (2023) implied that we need a plan of action toward standardized extraction to have more reliable and comparable MP data across studies.

The research done by Rajan et al. (2023) indicated that polyester and nylon fibers, which are the most plentiful types of MPs, are preferentially carried by MP filamentous structures. MP concentration has a direct relation to human population density and sewage discharge volume. Low-density polyethylene (LDPE), a leading form of the polymer in water samples, and polyamide (PA), a leading form in sediment, have been reported by Alam et al. (2023). The studies highlight significant plastic pollution in both wild and farmed fish from the Ganga River, with polyethylene being the most frequently detected polymer (Kumari et al. 2023). Among the four types of MPs (PE, PVC, PS, and PP), PE was reported to constitute 43.53% of the total harmful pollutants, PVC was 37.44% and PS was 19.07% (Farooq et al. 2023). The PE, PVC, and PP are prevalently the main MPs, which are responsible for the 10.2% rise in MP ingestion disease instance attributable to improper disposal of waste materials (Farooq et al. 2023). Nayal & Suthar (2022) found that MPs play a major role in contaminating MP in sediments and water as well as creating detrimental environmental health impacts in Dehradun and Haridwar (MPs). The MPs and sediments found in tributaries of Dehradun highly represent the findings of the study, indicative of high loads in their waters. Polyethylene (PE) and polypropylene (PP) were the most common types of polymers detected (Nayal & Suthar 2022).

Mitigating MP pollution in the Ganga River requires a multifaceted approach (Raha et al. 2021; Vaid et al. 2021). This includes enforcing strict regulations on plastic production and waste management, implementing effective wastewater treatment systems to reduce urban and industrial MP discharge, and improving solid waste management practices to minimize plastic debris (Rajmohan et al. 2019; Da Costa et al. 2020; Rajan et al. 2023). However, while these strategies are critical, their feasibility in the context of the Ganga River presents challenges. The enforcement of plastic waste regulations may face resistance due to the economic reliance on plastic products, particularly in the informal sector, which contributes to significant plastic waste. Similarly, upgrading and implementing effective wastewater treatment systems in the Ganga's extensive urban areas would require substantial financial investment and infrastructure development, which could be hindered by resource constraints and existing system limitations. Agricultural practices should also shift toward sustainable alternatives to reduce MP runoff from plastic mulch and fertilizers (Van Schothorst et al. 2021; Salama & Geyer 2023; Tang 2023). The shift to biodegradable plastic alternatives faces challenges, notably high costs and limited farmer awareness or incentives. Leveraging traditional knowledge, such as using natural materials in agriculture and sustainable waste practices, can aid in reducing MP pollution. Effective strategies include bio-based filtration systems using materials like mycelium or biochar to capture MPs in wastewater and advanced nanotechnology filters for industrial and municipal treatment. Bioplastics from algae and plants offer preventive solutions, while engineered wetlands and microalgae cultivation can naturally trap and degrade plastics, supporting an integrated approach to MP mitigation.

Community engagement through awareness campaigns and clean-up initiatives is essential, alongside investing in research for innovative solutions like advanced filtration and river-cleaning technologies (Balkrishna et al. 2024; Kang et al. 2024). While community involvement can help mitigate surface-level pollution, the long-term challenge lies in the complexity of removing MPs from the river system once they have dispersed and broken down into smaller particles. Advanced filtration systems and river-cleaning technologies show promise, but their scalability, operational costs, and effectiveness in large, polluted rivers like the Ganga need further evaluation. By integrating these strategies, we can protect the Ganga River's ecosystem and the well-being of the community dependent on it. However, overcoming the practical challenges will require a coordinated effort involving policymakers, researchers, industries, and local communities to ensure successful implementation and long-term sustainability.

Significant strides have been made in understanding MP pollution in the Ganga River, but critical gaps remain. Future research should prioritize the following areas to deepen insights and improve mitigation strategies:

• (1) Comprehensive source quantification and seasonal analysis: Future studies should aim to precisely quantify MP contributions from various sources, such as urban runoff, industrial discharges, and agricultural inputs, considering seasonal variations. A detailed understanding of source dynamics and temporal patterns will enable targeted interventions for peak pollution periods, such as monsoon runoff or religious gatherings.

• (2) Polymer-specific impact studies on aquatic life: The toxicity of different MP polymers, such as polyethylene, polypropylene, and PVC, needs further investigation to assess their specific impacts on aquatic organisms in the Ganga ecosystem. Research focusing on bioaccumulation pathways, species-specific ingestion rates, and polymer-toxicity correlations will provide insight into ecological health risks.

• (3) Innovative MP removal and degradation technologies: Developing and testing novel methods for MP removal, including bio-based filtration systems and enzymatic degradation processes, is essential. Pilot studies deploying such technologies in wastewater treatment facilities could evaluate their efficacy and scalability for broader application in river management.

• (4) Socio-cultural mitigation strategies: Given the Ganga's cultural significance, future research should explore community-driven approaches and culturally sensitive mitigation measures. Collaborative research with religious leaders and community stakeholders could identify and promote eco-friendly alternatives to ritual materials, fostering pollution-reducing practices that respect religious customs.

• (5) Public health implications: Few studies currently examine the direct impact of MPs on human health among communities relying on the Ganga for drinking water, fishing, and agriculture. Longitudinal studies assessing MP exposure through water and food sources, and the potential health consequences, are urgently needed.

MP pollution in the Ganga River presents a multifaceted challenge with profound ecological, socio-economic, and public health implications. This review underscores the urgency of addressing the diverse pathways through which MPs enter and propagate in the river. Urban and industrial effluents, agricultural runoff, improper waste management, atmospheric deposition, and riverine dynamics collectively contribute to the widespread distribution of MPs. These pollutants pose severe threats to aquatic life, ecosystem health, and the well-being of millions relying on the Ganga for sustenance.

The impact of MP pollution extends far beyond ecological damage. It compromises water quality, disrupts local economies, and poses direct health risks to communities dependent on the river for drinking water, agriculture, and livelihoods. Therefore, effective mitigation strategies must not only focus on technical solutions but also incorporate socio-economic and cultural considerations. Robust wastewater treatment infrastructure, stringent regulation of industrial discharges, improved agricultural practices, and enhanced solid waste management systems are critical to addressing the issue at its core. Public awareness and community engagement are indispensable, as they empower local populations to reduce plastic waste generation and adopt sustainable practices. Local knowledge and traditional practices, when integrated with modern mitigation strategies, can play a crucial role in enhancing the overall effectiveness of efforts.

To ensure long-term success, future research should prioritize the development of advanced monitoring and analytical techniques to understand the distribution, composition, and environmental fate of MPs. Additionally, innovation in technologies for MP removal and degradation must be accelerated, with a focus on scalable, cost-effective solutions suitable for large river systems like the Ganga. Specific actions should include the establishment of multi-stakeholder platforms for policy development, the adoption of regulations for biodegradable alternatives in agriculture, and the creation of incentives for industries to adopt cleaner production processes.

Collaboration between governmental bodies, scientific communities, industries, and local stakeholders is essential for designing and implementing sustainable, holistic solutions. By addressing these challenges proactively and with a clear focus on actionable solutions, we can safeguard the Ganga River, ensuring its ecological integrity and continued vitality for future generations. These steps, if adopted, will not only mitigate MP pollution but will also foster a more sustainable and resilient river ecosystem.

All relevant data are included in the paper or its Supplementary Information.

The authors declare there is no conflict.